gooderham



Aug. 12 1924. 1,504,231

J. W. GOODERHAM TELEPHONE EXCHANGE SYSTEM 1|. A. lwvm QQ *19% WU SW N. www M. www@ i 5, m Kw@ L Nv: 1 m Nn m3 mr: S 6

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' J. W. GOODERHAM TELEPHONE EXCHANGE SYSTEM Original Filed Nov. 50', 1920 6 Sheets-Sheet 5 Ed. A

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John W code/M Aug` 12 1924. 1,504,231

J. W. GoODE-RHAM TELEPHONE EXCHANGE SYSTEM original Fgled Nog. zo 1920 6 sheets-sheet s" u s y E 4 WML?? /m/en/arr I 3" Joh/7W Goode/hanf by A//y Patented Aug.. 12, 1924.

JOHN GOO' COtv'jPANY,

Wj, Si? NER/V T EL H N E 'Ffa/einher B, 1826, Serial No. 427,445.

etober im, 3.922.

V iff/mm, it mm/ concern.'

known tl JOHN WT. GOODERHAivr, ci the l f ited. States ott America, ret llfcnkers, in the county ot lifestaufl State oit New York, have inif'. .i certain new and useful. improvements in Telephene-Eschenge Systems, of which the 'Following is a t'ull, clear, concise, and cffact description.

This invention relates to a telephone system and more particularly to a system in which connections between suhscrihei"s lines are established by means of mechanical NovemberiSO, 1920.

in the installation et telephone exchanges n, m hun inchanieal switching mechanism .is tot' extending connections between lines, it is the usual practice to de 1the cinire exchange into a plurality of oliiccs and to make provision in each o'iiice for imahl 0 service to 10,000 subscrilf ers lines. The niiimber oit oiiices in the exchange is so selected that at the outset no (illicit required to :timction to its ultimate capacity and theretore only such switching` units are initie lj; installed in each oliice as are :essarjtr to care tor the immediate eX- pai iicn of the system. Als the demand tor service in any particular o'lhce inci-eases.y addi ifxnal switchin.0l u ,its are added until the ulti are capa is reached when a new oiliee is established.

@bviously during the period in which the demand 'for sewice is increasing, there must always he su. ing units which are not employed to their full capacity. This is esiiccnll): Jrue ot incoming selector switches which have access to small groups or divi-- sions ot trunk lines and to final selector h have access to the individual Thus there will be a number of terminal sets in the banks oli incomingselector switches which are blank .-r not connected to working trunk lines e. .tending to final selector switches, and terminal sets in the banks ot tin al selector switches which are blank or not connected to subscribers lines.

Ii the exchange operates upon a full mechanical basis, that is ching subscribers set onncctions by dialing the numbers of de ed lines to position the selector switches,

" remises, :naar venir,

ANGE

.SSGNOE TO WESTERN ELECTRIC CQRPQR-ATEON @39' NEVJ' YORK.

SYSTEM.

lvided and application filed. Sera Nn. 597,729.

or if the connections are established semimechanically, that is an operator causes the setting of the selector switches in accordance h instructions received from calling subscribers, it may be, as often occurs, that a selector switch will be set to extend a connection into a division of an oliice which has not yet been installed or a inal selector switch will he set upon a blank bank terminal to which no subscribers line has been connected or upon the terminal of a line from which former service has been discontinued. In such a case it is desirable to route such connections to a special operator-s position, sometimes called an intercepting operators position, so that the subscriber or operator may be informed that they have inadvertentestablished the connection to such a blank terminal.

lt is therefore an object of the invention to enr-.lne calls incoming over blank or unequipped terminals of selector switches to be answered without causing a charge to be registered against the calling subscriber.

A. 'further object of the inventoin is to provide a special cord circuit at an operators position for answering calls incoming to the position by virtue oi. the setting oit a selector switch upon a blank terminal set, and. equipped 'for tripping machine ringing with out causing the charging of a call upon the fs message register or coin A still 'further object of the invention is to provide a cord circuit for answering calls ot the nature et forth, equipped with means eiective for recalling a semi-mechanical operator in case the call was vestablished through such an operators position, but ineffective for charging the call on the calling subscriber-s charging device in case the call was established by full mechanical means.

The principal feature of the invention resides in the provision at the intercepting operators position of a cord circuit for anfring intercepting calls. The cord cir cuit is so designed as not to operate the changing relay of calling subscribers disi lt Vselector to charge the call on the sub scribers message register or to collect a dei'icsited coin, when the machine ringing is being tripped or when the operator operates her ashing key. The flashing key is profl-ll vided for recalling a senil-mechanical operator or a distant toll operator when the call has been routed to the intercepting position through such operators positions and it is necessary that this key shall not operate the charging relay in a 'full mechanical suhscribers district selector it the operator depresses the key upon such a calL 'lhe trip ping of inachine ringing is accomplished l connecting ground to the ring` conductor or the cord circuit for an interval long enough to energize the tripping relay7 but 'tor too short a tiine to perinit the chargingrelay to function to establish circuits tor chargingv the call, Siinilarl y the `flashing,` key establishes a circuit over the cord circuit for inoinentarily operating the supervisory relay of the semi-mechanical operators cord circuit or ot the toll operators cord circuit, but olf iiisutlicient duration to operate the charging` relay oil a 'full ineclianical district selector should the key be operated when a call has been extended through a tiill mechanical district selector.

Furtlfier Yfeatures oi the invention will be apparent troni the following' description considered in connect-ion i "h the acci'Y iiipanying drawings in which lr' l snows one of a group ot lines terminating` in :i toll mechanical o'llice ot the @Xchange sind rotary line switch individual to such line by ineans of which the suhseriliers line inav he connected to idle distri sei* switch; Fig. 2 shows a district selector :,iid sender finder switch together with the circuits and controlling' niechauisin i therewith; Fig, 3 shows diagraininaiticalljiY :i portion of a ieejiste sender which niay he associated with the district selector ot il 2 'for controlliugv the settingv oi" the selector switches; Fig, l shows an iii-comin(y fw. ooi we assoc i ated lector switch provided with inechai 'toi' aiiplying` ringing` current to the 'ter l;

of called lines together with the ci1 and niechanisin for controlll j such switch; l? shows the mechanisin and circuits of' ia final selector switch; 6 shows the and last trunl; lines ot a group et trunlr lines Xtending` from blank terminals ot the tinal selector switch ol 5 to an interceptiiig operators position and a cord viiciiit at the operatos position; Figi'. .7 shows a diagram of circuits over which connections inay be ators position; and Fig. 8 illustrates `the manner in which the several Afigures should be arranged to show as much ot a complete organization et circuits as is necessary to properly illustrate the invention. i

The calling suhscribers line l o' usual tap/*pe provided with a trensinitter7 i ceiver and call-bell and7 since it terminates in a lull mechanical exchange4` it is e equipped with the impulse sending dial of the usual type,

Xtended to an interceptine' opere4 rllhe suhscrihers line teri-iiaites truiih iindiiig swit step-by-step type wl j plurality et wipers ha access to a oi tiuil' l"= ,i terminet' i. 'tei is provided ',ieiL.,pir g;` ,nali/net tor advancing o the terminals oi' trunk lines "i en idle trunl lite anc to upon the release of tion.

'.lhe district selector ritcli conime" selector switch if 'l e lector 550 disci@ VJl and i the type shown si? isis.

A, e to 'att and l issued January f iiforii'led witl a verticz'zllj;

Vin t access to f Tgrmdriving' the i, lish set hay ing (l terminals.

`1iti'ft upwardly an up-drive nilN rei'V i* .,-fjl which when energized presses thc switch slia'tt c'aiiist a constantly driven Vf" power di'uin and tor restoring the switch to noi-inal position a second down-dri1rey niacjiiet is provided which .Then ene Zed presses the switch shaft against a second .lily (lGrlli' power drum. or L l ie particular set oit lii'iislies oe 'tch s istt to lie employed? a tripp r Y] is provided as descrilied 'Y it hereiul 'terred to. The iriiiai c on s t lll fore

wi i dA fers tronc the other Vl" tor swite ies in being provided with :idditional ineens co iprising; a secound niiant, drt i druni for drivin/g :ii sha'lit lly, whereby 'the jf: is driven :ipw j by the two up lW drive drunis at diffe speeds^ rapidi brush selection l e slowly duri L of the `iler switch fill shown in 1l" of the well ltiiown stei wipers liieiiifg; ailvaiieed hv i t to hunt Ylor an tutticall;v shown in litigi'. il. Th]

, i io norinal position the wipers llfi ne; ii contet iritli the benl: tei-1n s las! eniployeih when the switch is not iii useY @ply so iniicli oi the reg 3 as is neces is shown in Wie' understan ina-y he .i No. i, l?. il. tlcudder. November L H2L .i .f tions in the manner set 'torlth control the selector switches 250` 550.

ller centre-lliup"` the with the several se ector switches circuits oit the office senden anni' witches plurrfility oit contacts. The cani contacts sociated with each sequence switch closed onli7 in the position the numerals associated uut` s indicated by n each contat sito the exception et the master coi et" 201 E01`r` L101 and 501 associated, rf, ec-

tively, with sequence switches 2007 300; um and 500y these latter contacts being; opened in the positions indicated by tac numerata appeal." adiacent i such conta and closed in all other positionsa The different pieces of apparatus einv ployed in the system haring now been 'fully descrilied, it is thought that clearer uudei'standiiu o'` the invention maj,7 he hurl trom a description ot the method ot establishing a .onnection. lt will assumed tl at the calling subscriber at the substation h' desi ring a connection with a subscriber iu his own o'l'ice whose directorT number is Plilhlnsylranis 8432, through inadif'ertence dials the number corresponding to lFfNir Silvas-ria 0682 and that this latter number has not heen assigned to anyv subscribera but appears as a blank terminal in the banks of all final selector switches which have access to the group ot lines containing lines 8500 to 8999 inclusive.

The calling` subscriber to initiate a call reirioves his ,receiver 'trom its switchhook thereb;7 closing a circuit 'tor the line relay 101 ot the trunk hunting switch 100, which circuit may be traced trom grounded hatM tei-'y through the right` hand winding of Vre-A lay 101, the innermost lower armature and `back contact oi cut-off relay 102, over line conductor '103v` through the substation o.l subscribes line and then haelt orer line conductor 104 to ground at the upper arH mature aud back contact oi cut-ott relay' 102. The liuc. relayr cnergizes in this circuit and closes a circuit tor the stepping` magnet 105 ot the switch 100, which circuitmalr he traced trom groiuided battery through the winding'. armature and contacts o'l magnet 105. conductor 10S, the lowernost armature and back contact et relay 102 the right hand armature and 'iront contact oit relay 101 conductor 107l and thence to [f ground through the wiper 108 and the normal contact ot the heult to which this wiper has access. The magnet 105 upon energizing; iu tl circuit opens its energizing circuit at its armature contacts and the eupon dcei'ieruizes, advancing the wipers 108, 109, 110, 111, 112 and 113 ol switch 100 to the perm r l' 'to t "d- 1 trunk of the i 100 has access, st trunk of the group is ousr oe a ground potential on the test rect appearing in the lowermost bank oi the switch and the switch will therefore continue steppiinguntil an idle trunlt is tounrh upon the test terminal oit' which hatA tf-n',r potential appears, W hen such an idle truuk is tou l a circuit is closed from ba'l terjy through the contacts of sequence switch cam 202 (It) ot the district selector 250 to which the lirst idle trunk entend L Y' through ne inner lett hand armature ano hack contact oic sleeve relay 226 over test conductor 1141, wiper 108, conductor 107, lett hand armature and front contact and lett hand winding` of relay 101, conductor 115 to ground througi both windings of cut-olii rela;rv 102. Relay 102 is energized in this circuit and opens, at its lowermost armature und hack Contact and at its upper armature and back contact, the circuit previously traced through the winding oit step-- ping; magnet 105 and at its upper armature and trout contact and at its uppermost lower armature and front Contact extends the conductors 103 and 104 of the subscribers line to the wipers 111 and 113 ot the switch 100 and from thence to the trunl conductors 116 and 117 leading to the lected district selector. RelayY 102 also at its intermediate lower armature and trout contact closes u circuit extending;h through the right hand winding of sleeve relaj,7 ot the district selector switch? the hreal con` tacts o'lE the left hand armature of slow releasing relay 2271 the lower right hand contact of sequence switch cam (1 to 21) sleeve conductor 11S, wiper 109 win ot marginal message register magnet a conductor 120 the intermediate lower armaturc :u Y l'rout contact ot relai.' 102 and thence to ground through the upper winding; ot relay 102. rllhe sleeve relay 226 oft the district selector switch energizes in this circuit hut owing to its marginai nature the message register magnet 119 does not ener gir/le at this time.

For making the falling; subscribers line K bus)7 to all calls incomingv thereto, battery iiotential is connected to the multiples ot test terminalV 121 ot the calling line appearingv in the hanlrs ot all selectors having acc to this over conductor 122 the it `1 `tl armature of line preparatory to restoring tinder to normal when the cut-ofi relay 102 be comes deenergif/,ed upon the termination o; the connection.

pon the enei 4 ai' circuit is established tor 22S or the district selector circuit Atends l'roin through the rignf l i n ling or relay, the lower right A.and contact quence switch cam conductor 22 lower contacts ot sequence switch can, f conductor 230 and thence to ground thi' the front contact and if-ight hand arm; ot relay ziet its inner lett hand ari c ture and bach contact 220 opens the initial energizing circuit previously traced extending through the windings ott relays 101 and 102 and at its lett hand arniat and front contact connects ground potemri to the test conductor 1111 et the selected trunk to mark the truuls busy to other liuc switches.

Relay 228 upon energizing closes a circuit tor driving the'sequence switch 200 of the district selector switch out ot its normal position 1 and into position 2, this circuit extending fromv grounded battery through the winding ot the driving magnet of switch 200, conductor 231, the upper lett hand contact ot sequence switch cam 200 (1), the inner right hand arniature and front contact of' relav 228, and thence to ground at the lower right hand contact of sequence switch cam 20'4 (1 to 6). The sequence switch magnet energizes in this circuit and under the control ot master cam 201 drives the sequence switch into position 2 in which position the circuit previously traced over cani 202 is Opened and a circuit is closed 'from grounded battery through the winding of relay 227, the upper left hand contact ot' sequence switch cani 208 to 11) and thence to ground,`

Relay 22T upon energizing closes a locking circuit for the sleeve relay 226 extending through the right hand winding et relay 226, the make contacts of lthe lett hand armature ot relay 227 and thence to the sleeve conductor 11S over the upper contacts et sequence switch cam 208 (13/4c to 10), this circuit being maintained through position 16 of the sequence switch or until relay 227 becomes deenergized. Upon reaching position 2 the sequence switch connects a new holding ground to the test conductor 114i eX- tending trom conductor 1111 over conductor 232 and through the upper right hand contact ot sequence switch cam 208, which holding ground is maintained through position 181/4 or" the sequence switch.

)when the sequence switch reaches position 1%, a circuit is closed 'for the stepping inagnet 233 cit 'the sender finder Sli", extending troni grounded battery through the interrupter contacts and winding oit magnet the upper lett hand contact et sequence switch cani 200 (1% to 2), conductor and thence to 'fround through the inner right L armature and trent Contact ot rela the lower right hand contact witch cam 205.7 (1 to 6). cir-- s s winding o;

t Tying magnet 23S, the windeut-in relay O o and thence to ground at the lower lett hand contact ot sequence switch cani 208 (2 to 11). Relay does not energize at this time, however, since its winding is shunted by ground connectedv through the armature or" .ine relay .its soon as sequence switch 200 leaves position 1, the initial energizing circuit of line i relay opened at the lower right ha contact ot sequence switch cani 201?, but this relay remains loci-Ted over a circuit entending from grounded battery, its lett hand er mature and trent contact, the upper le'it hand contact el sequence switch can; 210 (1 to 6)n conductor the lower right hand contact ot sequence switch. cam 211 (1 to 21;), conductor 23'?, test wiper 23S of the sender finder switch and to ground on the contct with which the wiper 238 is in mg; nient, it the oliice sender which is then 4issocrated with the district selector through he wipers oit switch S is at the time busy. '.llhe stepping magnet 33 energizes in the circuit previously traced opening its own circuit at its armature cont-acts thereby causing its own deenergization to advance the wipers oit the switch SF one step. lt the test wiper 23S then engages a contact corresponding to another busy sender, line relay 228 remains locked up and the circuit for stepping magnet is again established. ln this manner the nignet 233 advances the wipers or the tinder switch until an idle otlice sender is found when the wipe-r 23S will find no ground on the terminals corresponding' to such idle sender and the line relay 228 will thereupon deenergize. Relay 228 upon deenergizing, opens at its inner right hand armature and trontcontact, the circuit extending through the stepping magnet thereby arresting the stepping movement of the switch Sli, and closes at its inner right hand armature and bach contact a circuit 'for driving sequence switch 200 out ot position 2 and into position. 3. This circuit niay be traced from grounded battery through the winding of the magnet ot sequence switch 200, conductor the upper right hand contact of sequence switch cani 200 the inner right hand armature and bach contact oit relay 228 and thence to ground at the lower right hand contact ot sequence switch cani 207. Als soon as line relay 22S deenergizes, the shunt around the win-fl' of relay ren! 'red L' closed at this time through the yar( inner right l'iand armature and front contact oil` relayv 223 andreiay 235 there pon energzes in series with stepping magnet 233, the current tiowing through its circuit not being suiiicient to cause the energization ot the stepping magnet because ot the high resistance olf the winding ot relay 235. Relay 235 upon energizing chr a circuit extending trom ground through its inner lett hand arn'iature and Yfront contact, over wiper 23 and the terminal upon which it is resting, conffluctor 302 and thence to grounded battery through the winding oit relay 303. Re lay 303 energizes in this circuit and at its armature and contact establishes a circuit tor rrelay 304 which latter relay at its armatures and contacts closes an impulse circuit extending through the windings ot the impulse relay 305 and over the calling subscribers line loop. rllhis circuit may be traced trono grounded battery through the left hand winding ot relay 305, the left hand armature and contact ot relay 304, conductor 30G, wiper 239, conductor 240, the upper lett hand contact of sequence switch cani 212 (2 to 101,) conductor 117, wiper 113, the upper armature and iti-ont contact ci relay 102, conductor 104, thence over the subscriberls line loop and returning over conductor 103, the innermost lower armature and iront contact of relay 102, wiper 111, conductor 116, the lower contact ot sequence switch cam 2l3 to 101;), conductor 241` the outer leit't hand armature and tront contactI ot relay wiper 242, conductor 307, t-he right hand armature and contact of relay 304 and 't hence to ground through the right hand winding oli impulse relay Ground potential connected to the wiper 238 through the inner lett hand armature and trout contact ot relay 235 also establishes a busy potential upon uuilt-iples ot test conductor 302 to prevent other sender iinders troni selection; the sender which has now been taken tor use by the calling subscriber.

The calling subscriber now proceeds to dial the number oit the desired line. Under the assumption that. the suhscriber desires a connection with the subscrihei"s line which listed in the directory as PlNnsylVania V@strict selector switch 250` an incoming selector 450 and a [inal selector 550, the sub- 'iber proceeds to dial three letters correH spendiv to the oilice designation ot the o'tlice in which the desired line is located and then dials tour digits representing the num bei' ot the line in such otlice. 1n the case assumed the calling subscriber will dial the letters PEN and then should dial the nuinea-als 3432, but through inadvertence dials 'the numerals 8632. The three letters which represent the oiiice code causes the setting oft the codo registers in thc o'licc sender in the niunner fully set Aforth in the aforesaid f and that this line is reached through patent to l?. A. Stearn and F. J. Scudder .vliich, through the mechanism associated with the sender, controls the setting of the district selector switch 250 tor extending the connection through the desired office of eX- change, in this case to an incoming selector in the subscrihei"s own otlice.

The dialing ot the numerals 8632 causes the setting of the numerical register ot the sender in the manner set forth in the aforesaid Patent No 1,395,977 for controllingthe setting of the incomingselector switch 450 and the iinal selector switch 550. Following the setting of the code registers oi the sender, the sender sequence switch 300 is moved from its normal position into position 2 in the manner set forth in the atoresaid patent, and the fundamental switch controlling circuit which extends trom the sender to the selector switch 450 is closed at sequence switch cams 308 and 321., This circuit may be traced from grounded battery through the lett hand winding of relay 223 of the district selector switch, the upper right hand and lower left hand contacts oit sequence switch cani 210, conductor 243.l the inner right hand armature and front contact ot relay 235, the wiper 244 ot the sender finder switch SF and the contact ot the bank with which this wiper is associated, conductor 309, contact of sequence switch cam 308 (2), windings of over-flow relay 318, windings ot sender steppingl relay 310, the armature and back contact ot the No. counting relay 3117 and thence to ground at the right hand contacts of sequence switch cani 321. The .line relay 228 ot the district selector switch and stepping relay 310 ot the oitice sender both energize in this circuit.

Relay 228 upon energizing closes a circuit t'or driving sequence switch 200 out ot position 3 and into position 4. This circuit extends from grounded battery through the magnet winding` ot the sequence switch 200, the upper lett hand contact of sequence switch cam 206 (3), the inner right hand armature and front contact ot' relay 228 and thence to ground at the lower right hand contact ot sequence switch cam T (l to 6). W ith the district sequence switch 200 in position 4, a circuit is now closed for the updriye magnet 245 ot' the district selector., which circuit entends from `grounded battery through the winding ot magnet 245, the upper right hand Contact of sequence switch cam 209 (4), conductor 234, and thence to ground through the inner right hand armature and trent contact ot relay 223 and the lower right hand contact ot' se quence switch cam 207, Magnet 245 upon energizing presses the depending portion of the switch shaft 246 against the constantly rotating updrive drum 247 thereby causing 'he upward movement of the switch sha'tt. Upon the movement of the sequence switch of hrushes is new tripped upon the upward moi/erneut ot switch shalt .iai

nl l l i x 1 "i l vn Yl 73- ...au tuning ac con inner. npi. LLit inoic .iai nient et the switch shaft,y the tripped set oit brushes travels over the contacts oit the bant. with which they are associated. rllhe inaining tour sets oit brushes not be Y tripped are tunctionless at this tiine. :Dui i the continued upward nioveinent ol the switch sha'it and as the tripped wuduetor 254i.) segnient 9.55, brush 256 and thence to ground at the lower contact o't' sequence switch cani 214i to 7). Further ujiiiward iuoren'ient oil: the switch shaft advances the brush 256 into engagei'nent with an insulating portion oit segnient thereby removing the shunt troni around the winding olf stemging relay,7 Slt). The intermittent connection of this shunt around the windings ot stepping relay 310 causes the intermittent energization and deenergization ot stepping relay 3l() whielu in the wellhnown n'ianner, causes the successive energi- ./.ation oit counting relays associated with the sender.

liVhen the sender has been satistied with respect to the district group selection condition which has been established therein through the setting ot the code registers by the calling subscriber, the No. 0 counting relay Bill becomes energized closing the eircuit ot' Vthe No. 0 counting relay 231]. which locks up .in series with relay 313 through the contact ot sequence switch cani Bit (41), lflpon the energization oi relay Bil.` the circuit previously trared through the magnet wiiuiling ot sequence switch 300 again es tablished and the sequence switch 300 driven out oit position el and into position tl( At its le'it hand armature and bachY conact relay Sil opens the Afundainental circuit. thereby causing the deenergization ot relays lill and 29.8, las soon as sequence switch im() leaves position +L, the locking circuits ot Vthe energized counting relays are o1 3 and "ned :it lille sequence switch cani .fir these relays deenergizze, frs soon Afollowing the opening o'i, the Yfuiidan'iental circuit .s the brush 256 engages the next. insulating portion of connnutator segineiit 255, rehiy i) deur 'ses opening at its inner right hand armature and trent. contact. the circuit previously traced extending through the winding of the updrive magnet lite thereby arresting the upward inorenient winding? the lower right hand Contact ot sequence cani 201i (l to tpl-)j conductor 229, the lower contacts of sequence switch cani 205 and to lb`round at the right hand arinature and Ltront Contact oi sleeve rela7 2%. Relay 228 upon energizing, closes a ci cuit 'for driving sequence switch 700 out oft po sition i and into position 8. 'lhis circuit may be traced `trein grounded battery through the magnet winding olf the sequence switch conductor 28' the upper lett hand Contact of sequence switch cain 206 the inner right hand armature and `iront Contact ol' relay 22S, the upper lett hand contact ot sequence switch cani Q07 (7 to 8) and thence to ground through the inalre contacts ot the right hand armature ot relay 227.

As soon as sequence switch 200 leaves position 7, the initial energizing circuit of relay 228 is opened at sequence switch cani 204 but relay 228 locks up over a circuit extending 'troni grounded battery through its lett hand winding, its lett hand armature and Yfront contact, the upper contacts of Sequence switch 2],5 to the test brush 9257 and if the first truuk of the selected group is busy to ground at the test terminal ot this trunk. Upon reaching position 8 with relay energized7 a circuit is established tor the updrive magnet 245 which niay be traced `.troni grounded battery through the magnet 245, the upper right hand contact of sequence switch cani 209 (Si), the inner right hand armature and liront contact oi? relay and to ground at the lower right hand contact of sequence switch cani 20?. The updrire magnet 24:5 upon energizing again drives the switch shaitt upvardly in search olV an idle trunk in the Selected group. Se longas the test brush encounters the terminals of busy trunksy relay 228 remains locked.Y Villieiu however, an idle trunk is encountered which it will be assumed is the 'trunk ter-- ininating in terminals 259 and 260, the locking circuit of relay 22S is opened and relay 228 deenergizes as soon as the brushes Q58 and 261i have been properly centered upon bank terminals 258, 259, and 9,60. Until the brushes are so centered 228 remains locked up over a circuit extending thro gli its right hand winding, the lower left hand Contact oit sequence switch cani 201i (8), conductor 286, centering segment 287, brush 288, the lower lett hand Contact Hifi shaft 2% and closes a circuit extending througl'i its inner right hand ar'--iature and hack Contact over sequence switch cain 20@ (8) for driynig sequence switch 200 out o1? connected to the multiple test t selected trunk over brush 2K? hand contacts of cani 215. R energiyes when sequence switch position 9 over a circuit extendin through its rigl'it hand 'i'ivinding7 the lower right hand contact of sequence switch cani 201i- (9 to l0)j conductorI 2297 the upper lett hand and lower right hand contact of sequence switch 205 and to ground at the rightl hand arinature and front Contact ot relay 26h l-elay 261 is at this time energized over a circuit extending from groundedL battery through its Winding, the upper lett hand contact et sequence switch cain 216 (4L to 10), the outer right hand armature and trout contact ot relay 285, the lower right hand contact oit sequence switch cam 217 (3 to 10)./ Wiper 262 of the sender i'inder switch SF, conductor 316 the armature and hack contact of advance relay 317 and thence to ground.

Relay 228 upon energizing in the circuit previously traced closes circuit througl'i its-i inner right hand armature and liront cositact for driving sequence switch 200 out et position 9 and into position 10, in Wl'iich position 'the fundamental circuit is extended through contacts ot sequince switch canis 218 and 219 over brushes 263 and 264 of the district selector' switch to the line reley A21 ot the incoming selector switch 450. r1`his circuit may he traced from grounded battery through the right hand Winding of relay 421, conductor 4227 the upper contacte ot' sequence switch cain L102j conductor resistance element 1124;, the uppi r contact olf sequence switch cain 403 (1 to l0) triniiconductor Vi219., bank terininal 260 and brush 263 oi the district selector switch 25()j the upper right hand and lower right hand contacts of sequence switch 218 conductor 2641 conductor 241% the inner rig` hand arnr ature and front contact of relay #135, Wiper 21111, conductor 309, the contact of sequence switch cam 308 (6), the windings of overflow relay 318 and sender stlpping relay 310, the armature and back contact ot' counting` relay 3117 the upper contacts of sequence switch earn 321, conductor 312j Wiper 2657 conductor 26o7 the lower lett hand and right hand armature and trent Contactor'zH 'iand trent contact c. sequence switcl'i s vicl` c i 10"? to 1G). fpiencc switch 00 leaves potuti-on in ial energizing circuit of opened at. the upper left 1+ [faience ritch cani lf2 mains energized over the j.'

cuit through, a locking' branch (Tit iii i .i etal circuit which may he trai 'minded battery' throi'igh the rio'l 'winding' oi relay 4217 the right hai i' tacos ot sequence s h cani con'lnff- 95 tor L,1l-28` the right hand ature :and front Contact o'l3 relay 421, conductor 429. the lett hand contacts ot' sequence switch cani i108 (1 to ll) and thence over the huidainental circuit as previously traced. IU

lin position 2 ot sequence switch muy :t circuit is closed the updrire in 2%() which may he traced Ytroni grounr ,d tery through the winding` ot this magnet,

the upper right hand Contact ol seilguence switch cani 409 (2)j conductor 11i-l1, the one; left hand armature and liront contact if relay 121 and tliei'ice to ground at the lower contact of sequence switch cani 407 l'ilaenet e230 upon energizing presses the dcjiicndi j portion ot the switch shatt L32 against t constantly rotating updrive di-unr 'ing thereby the upward nioye switch As .the shaft oil the proaches its iiirst lernsh t'pping position.r` hrush 436 engages a metallic portion ot the brush selection segment or' the w e nuit-eter 135 and a circuit is closed if; Y ot 'une stepping' relay 3110 ol the of -which may he traced from nroun llli lay 121, conductor 429, the upper lett haul contact of sequence switch com L08 (1 to il-L the lower right hand Contact ot sequence switch cani 4:08 (1iY to 2) segment 4341A, hrusl 186, conductor e137 and thence to ground it the lower contact of sequence switch cani l1() (T to 5). Upon the establislunent ot this shuuk relay 419i inaintaiir d energized over the shunt Inl stepping relay B deenei'izes. s the .switch sha it i continues in upward in rein tie brush e136 engages an insulating portion of the segment- 134 and the previously traced shunt opened7 whereupon stepping rel t euergizes. Yin this manne." :is t shaift mores upwar'lli' the L, pini? relay B10 ot the oilice sender is internintently energized and dcenergized to successively energize and .loclr up counting relays associated with the sender`r all in the well known manner.

1t has been assumed that the calling: sublscriber has dialed Nd. S632 and that, therefore the numerical registers ot the sender have been set to register this number. ihe No. t counting relay was theretmfer ener-gi upon the initial enerj'ization ot step relay when the Ytundainental circuit {irs-t extended through the winding` relay i-i o'l the inccini. selector switch. There'tore when the switch shailit oif the incorniwzl selector switch hw moved upwardly to such an extent as to position the h'lith set of ln'ushes thereon in such a relation to the tripping spindl` to lntn' cause the trip o oi this articular set oi brushesm the counting relays succeeding the No. l counting relay will have become eucrgijizefl and locked up and the i, O countii N' relay S11 will open the fundamental circuit at its lett hand armature and bach; cmitactD At its right hand armature and :Front conta ct/` relayV 311 establishes the pre viouslv traced ircuit 'lier driving` se t switch 3N) out et position 6 and ir Q lVh/en the scour ce switch lcavf (L the locking cir/uit "f p ing relays nrc opfncil at sequence switch cum and the countinorelays deencrn'ize,

its soon iiollowmg the opening ot the fundamental circuit by the No. il countingrelay 31 1 as the brush 4:36 engages the next insulating portion ot coinniutator segment line relay :l becoi es deenergizedi opening at its outer lett hand armature arl 'liront Contact the circuit of the updrive no ffnet 130 thereby arrestingr the upward increment of the switch shalt and its inner lett hrnfl armature and baclr contact closing" a c cuit tor chivinfi` sequence z itch f-li'out of position i3 and into posi- '.lhis circuit rnev be. 'traced tir-oni d battery throi i the magnet wind sequence switch y41.10.. l upper l coun troi ine; oit

tde A ch cani 406 (2) Y roer lei'- hand controL .oft relay7 position 3 switch f rcuit tor the pu magnet .troni grounded battery winding l/E8 and thence to ground through the right hand contacts o? seouenco switch cam LM15,v Magnet LM38 u pon energizing rotates the tripping spindle into such a position as will trip'the selected s t brushes, which in the case is t` e fifth set ot brushes, upon subsecuent upward movement of the tch shaft 4:32. ligen reaching` position 3 the fundamental kii extending through the winding oi A1 and the windings of stepping o1() and overflow relay 318 is again 1 over the circuit previously traced Relay 421 upon energizing in this circuit again closes the circuit previously traceifl tor driving sequence switch Zl0() out ot position into position 4L. and at its right hand armature and 'iront Contact closes the locking circuit previously traced for maintaining itself` energized over the tunda-` tiental circuit after the sequence: switch 400 leaves position 3g .Vith sequence switch 400 in position l and relay 421 energized, the circuit previously traced through the uprlrive magnet 1130 is again closed and the switch shatt 4:32 is again driven upwardly. During the initial upward movement of the switch shaft the tif-th set of brushes is tripped by the tripping spindle. and during the subsequent upward movement ot the switch shaft the tripped set of brushes travels in engagement with the terminals oi" the bank with which they are associated, and as the brush sha'tt ot the selector switch nieves the trippec set of brushes into engagement with the lowermost group et terminals in the bank1 brush L41Y engages the metallic portion ot the group n selection segment 440 ot the commutator battery through the right hand winding of relay 421, conductor 422, the right hand contacts ot sequence switch cam 02, conductor 452,8j the right hand armature and Ytroni'. contact et relay 4217 conductor 42a the upper contacts of sequence switch ca in 1109 cominutaitor segment a0 brush i451? conductor 4137 and thence to ground the lower Contact of the sequence switch cam 410 (7 to Eelay L21 is maintained enerrjized over this unt circuit, but stepping r 310 deenergizes, As the switch' shaft lcontinues inwits upward movement., the brush 44:1 engages an insulating portion of segment .5A-G and the shunt circuit is opened and stepping relay 310 again cnergizes. In manner as the switch shaft 432 cones its upward movement, the stepping y 310 of the sender is intermittently energized and deenergized.

this time the thousands and hundreds ,-erical regisi'gers ci the sender so set :is to provide a circuit :tor the No. 1 countlector switch, relay L121 ot the incoming selector switch. which was energized in position 7 of sequence switch A00 is maintained energized in position olf the sequence switch 4,00, over a circuit extending trom grounded battery through the right hand winding of relay 421, conductor l122, the right hand contacts of sequence switch cam L102, conductor 128, the right hand arinature and front contact ot relay 21, conductor 129, the lower right hand contact ot sequence switch cam 114; (7 to 8), brush 4h18 and terminal L1:4[9 of the incoming selector switch, trunk conductor 519, the upper lett hand and lower right hand contacts ot sequence switch cani 505, resistance element 520 and thence to ground through the lower' lett hand contact of sequence switch cam 506 (1 to Busy ground potential is placed on the multiples of test termina-l 451 of the selected trunk over test brush L142 and the lower right hand and upper lett hand contacts oi sequence switch cam 112.

Upon the extension ot the fundamental circuit to the inal selector switch 550, with the sender sequence switch 800 in position 10, relay 518 of the iinal selector and step ping relay 810 oi' the oll'ice sender energize. .Relay 518 upon energizing closes a circuit `lor relay 521 which may he traced from grounded battery through the lett hand winding oit this relay, conductor 522, the upper left hand contact ot sequence switch cam 507 (1), conductor 523, the left hand armature and viront contact of relay 518 and thence to ground through the upper contact of sequence switch. cam 508 (1 to 11). Relay 521 energizes in this circuit and at its lett hand armature and Yfront contact closes a locking circuit ttor itsel't extending from grounded battery through its left hand winding through the armature and back contactrof test relay 524i, the left hand armature and iront contact of relay 521, sleeve conductor 525 o1 the trunk circuit extending hack to the incomingselector switch, bank terminal L51 and 1crush LP12 ot the incoming selector switch and thence to l.Oround at sequence switch cam i12. Relay 521 upon lenergizing also closes a circuit for driving sequence switch 500 vout or its normal position 1 into position 2, which circuit may be traced from grounded. cattery through the winding of the magnet of sequence switch 500 through the lower contacts of sequence switch 509 and to ground at the right hand armature and front contact of relay When sequence switch500 moves out of position 1, the initial energizing circuit .of relay 518 is opened at the lower lett hand Contact of se VIVuence switch cam 503, but relay 518 remains energized over ,the fundamental circuit by reason of a loching circuit rextending vtroni gronndedhattery through the left hand contact of se quence switch cam 504, the right` hand winding oli' relay 518, the lower right hand contact oiE sequence switch cam 510 (15 to 10), the right hand armature and trontcontact of relay 518, the lower rifrht hand contact ot sequence switch cam 003 (1 to 6), and over the fundamental circuit as previously traced.

Relay 518 upon energizing, with sequence switch 500 in position 2, closes a circuit or the high speed updrive magnet 526 which may be traced from grounded battery through thel upper right hand contact of sequence switch cani 511 (2), conductor 523, the lett hand armature and front contact oi' relay 518 and thence to ground at the upper left hand contact of sequence switch cam 508. Magnet 526 upon energizing presses the depending portion of the switch shaft against the constantly rotating high speed drum 528 thereby causing the switch shaft to be moved upwardly at a high speed in its brush selection movement. As the brush shaft approaches its lirst brush tripping position, brush 582 engages the metallic portion of the brush selection commutator segment 580 of the commutator 531 and a circuit is closed in shunt of the windings ot the sender stepping relay 310, which may be traced 'from grounded battery `throng the left hand contact ot sequence switch cam 5,0/1, the right hand winding of relay 518, the lower right hand contact of sequence switch cani 510 to 10), the right hand armature and front Contact of relay 518, the lower right hand Contact oi sequence switch cani 508y (1 to 6), the upper righthand contact o't sequence switch 'cam 502 (151A to 2), conductor 529, commutator seg# ment 580, hrush 582`r conductor 538 and thence to ground through the upper left hand Contact ot sequence switch cam 506 (13to 11). `Upon the establishment of this shunt circuit relay 518 at the linal selector switch is maintained energized, lout stepping clay 810 of the oliice sender deenergizes,

;-is the switch shaft 527 continues in its upward movement, the brush 582 advances into engagement with an insulating portion of thecomniutator segment 580 and the shunt circuit previously traced is opened, whereupon sender stepping relay 310 again energizes. In this manner the switch shaft 52T continues its upward movement, stepping relay 310 ot theoliice sender is iiiterrnittently energized and deenergized.

On the initial closure of the fundament-al circuit through the winding ot relay 518 the windings ofpstepping relay 810, with the sender sequence/switch 300 in position 10, and under the assumption that the callL subscriber has set the hundreds register the sender in position six, a circuit is closed the well known manner for the No. 1v counting rela/y. In response to the' ico iso

intermittent energization and deenergization of sender stepping relay 310, the counting relays energize and lock up in succession in the well known manner until the No. (l counting relay 313 becomes energized, when an energizing circuit tor the No. O ccunting relay 311 is established, extending from grounded battery through the windings ot rela-y 313 and 311, the armature and front contact of relay 313 and thence to ground through the contact of sequence switch cani 315 (10). Counting relay 311 upon energizing closes a circuit at its right hand armature and front contact, extending' through the contact of sequence switch cam 314i (10) for driving sequence switch 300 out of position 10 and into position 12. When the sequence switch leaves position 10, the locking circuits of the energized counting relays are opened at sequence switch cam 315 and these relays deenergize. At its lett hand armature and back contact relay 311 opens the fundamental circuit previously traced through the windings of stepping relay 310 and relay 518 of the inal selector switch.

As soon following the opening of the fundamental circuit as the brush 532 engages the next insulating portion of the commutator segment 530, relay 518 becomes deenergized and at its lett hand armature and iront contact opens the energizing circuit o'f the updrive magnet 526 to arrest the upwardmovement oit the switch shaft. At its left hand armature and back contact relay 518 closes a circuit for driving sequence switch 500 out of position 2 and into position 3, this circuit extending from grounded battery through the winding of the sequence switch magnet 500, the upper right hand contact of sequence switch cam 512 (2), the left hand armature and back contact of relay 518 and thence to ground at the upper contact of sequence switch cam 508. The second set of brushes has now been positioned with relation to the tripping lingers of the tripping spindle 534 so that upon a subsequent upward movement ot the switch shaft, this set of brushes will be tripped for engagement with the bank of one hundred terminals with which this brush set is as sociated. To cause the tripping ot this set of brushes the tripping magnet 535 is energized as soon as sequence switch 500 reaches position 3, over a circuit extending from grounded battery through the tripping magnet- 535 and thence to ground at the lower right hand contact ot sequence switch 506 (3 to 5). `When sequence switch 500 reaches position 3, the energizing circuit of relay 518 is again established over the fundamental circuit as previously described and relay 518 and stepping relay 310 of the office sender again energize. Relay 518 upon energizing closes the previously traced cirincensi cuit Jfor driving sequence switch 500 out ot position 3 and into position fl, lilith quence switch 500 in position 4, the pre-- viously traced circuit 'tor the updrire magnet 526 is again established at lett hand armature and front contact oit relay 518. Relay 518 also establishes the previously traced locking circuit i'or itselt extenfl` g hrough its right hand armature and Yfrom' contact for maintaining itseli energized over the fundamental circuit after the sequence switch 500 leaves position 3 and the initial energizing circuit is opened at the lcwer lett hand contact of sequence switch cam Upon the energization ot updrive magnet 526 the switch shaft 52'? is driven upwardly in its group selection movement, and during the initial portion of this movement the second set of brushes is tripped by a linger ot the tripping spindle 534. During the remainder of the group selection movement, the tripped set of brushes then travels upwardly in contact with the terminals of the bank with which they are associated. is the tripped set ot brushes approaches the lowermost set of contacts ot the first group in the banlr, brush 538 engages a metallic portion ot the group selection commutator segment 537 of the commutator 531 and circuit is closed in shunt of the windings ot the sender stepping relay 310, which may be traced from grounded battery through the lei't hand contact of sequence switch cam 504 (l to 10), the right hand winding ct relay 518, the lower right hand contact or quence switch cam 510 (15 to 10), the rig-lu" hand armature and 'front contact oit relay 518, the right hand contacts oit sequence switch cam 503, conductor 536, coininutator segment 537, brush 538, conductor and thence to ground at the upper lett hand contact of sequence switch cani 506 (13 'to 11). Relay 518 at the inal selector switch is maintained energized over this shunt circuit but the sender stepping relay 310 becomes deenergized so long as the shunt circuit is maintained.

As the switch shaft 52'? continues in its upward movement the brush engages an insulating portion of the coininutator segment 537 and the previously traced shunt circuit is opened and stepping relay 310 ot the sender again energizes, ln this mani er as the switchshaiit continues its upward movement, the sender stepping relay 310 intermittently energizes and deenergizes.

Upon the initial energization of sender stepping relay 310 with the sender sequence switch 300 in position 12, it being assumed that the calling subscriber has set the register upon its third position contacts, a circuit was established for the No. 3 counting relay in the well known manner. ln response to the intermittent operation of the sender Stepping relay 310, the counting retong;

fit)

Ait)

lays energize and lock up in succession until the No. O counting relay .S315 becomes energized hen a locking circuit is established through its winding. the winding of No. O countingY relay ill lr1 the ariuature and front contact ot relay 313 and to ground at the contact ot the sequence switch cam 315 (12). Relay lll upon energizing` closes a circuit extending througli its right hand armature and contact, the contact of sequence switch cani 314i; (l2), and through the winding of the magnet ot sequence switch B00 for driving; serpiente switch 300 into position 14. At Vits lett baud. armature and back contact counting, relay Ell opens the fundamental circuit previously traced through the windings ot sender stepping relay 3l() and the winding` ol relay 518 at the final selector switch.

its soon following the opening of the il'iuulainental circuit as brush 538 engages the nent insnlat-ing` portion ot commutator segment 537, relay 518 becomes deenergized and opens the circuit previously traced through the wiudii'ig of the updrive magnet and closes the circuit previously traced .tor driving sequence switch 530() out ot position -land into position ln position 5': the liundanientnl circuit extending` through the windings oit step sing relay 3l() and the right hand winding' ot relay 51B is airain established. Relay ilS upon energizing); closes the previously traced locking circuit. tor itself and closes a circuit for driving; sr nce su" h 500 out of position 5 and into position G. Upon reaching' pos1- tion o., a circuit is established tor low speed updrive magnet 539 which circuit may be traced from grounded battery through the windingI ot' magnet i339., the lower lett hand contact ot seruieuee cam 507 (6), conductor 523, the letthand armature and 'liront contact ot relay 518 and thence to Le'rmnid at the upper lett hand Contact ot sequence switch cani 50S. The. low speed updrive 1 'i upon energizing preses the deportion ot the switch shaft 52T my nth' rotatingl low speed there v causing the upward movement oli the switch sli-att in its Vunits selection niovenieut.

its; the tripped set ot brushes approaches the lirst set ot terminals in the selector lirroup the brush a metallic portion ot the units selection portion ot conunuizitor segment and a circuitis closed in shunt ot the windings ot sender stoppin@ re ay 310, which may be traced from @rounded battery through the ieilft hand contact ot sequence switch cani fill-1. (l lo id), the right hand winds ine; ay Bt, the lower right hand tact ot' sequence switch cam 503 (l to 6), the upper right hand contact ot semence switch cam 50:2 to 6), conductor 529, commutator segment 530, brush c ductor 533 and thence to ground at ne ripper lett hand Contact ot sequence switch cam 50G. Relay 51.8 is nniintained energized over this shunt circuit but sender stepping relay deenergizes.

As the switch shaft 52? continues its upward movement, brush 53:2 comes into engagement with an insulating` portion of the comnnitator segment 530 and the previously traced shunt circuit is opened, whereupon the sender stepping relay 310 again energizes. In this manner during the continued upward movement ot the switch shaft the sender steppingl relay 3l() intermittently en ergizes and deenergizes.,

Upon the initial closure of the 'fundamental circuit ror controlling the units selection movement ot the linal selector switch, with the sender sequence` switch 300 in position let and, under the assumption that the calling subscriber has set the units register upon its fifth position terminalsa a circuit is established in the well known manner for the No. 2 counting` relay. ln respense to the intermittent operation of relay 310, the counting relays energize and loclr up in succession until the liloi 0 countinl relay 313 becomes energized? when a loclring' circuit is established for this relay as previously traced through the windii Y the No. O counting relay 311. Relay Sill, upon energizing closes the previously tracef circuit extending` through the cout J' sequence switch cani 314- lor drivingthe sender sequence switch 300 out ot position le and into position 1G. it its lelt hand armature and back contact relay 311 opens the 'fundamental circuit previously Vtraced relay 3l() and the right hand vinding; oLv relay 518 at the tina] selector' switch.

As soon Afollowing' the opening ot the iundamental circuit as the liirush e1 gages the' next insulating` sentaient oi;L comn mutator 530, relay S becomes deem 'fie-,il and thereupon opens the circuit oit the up drive magnet to arrest the upward 5"' and closir switch cam 510 and thence to ground at the right hand armature and front contact of relay 521. Relay 518 upon energizing` closes a locking' circuit for itsel'lz extending` from grounded battery through its right hand winding, the lower right hand contact oi? sequence switch cam 510 (15 to 10), the right hand armature and 'front contact of relay 518 and thence to ground through the upper contacts ol" sequence switch cam 513 (9 to 10). This lockingw circuit will be maintained. through position 10 of sequence switch 500. Relay 51.8 upon energizing` also closes a circuit as previously traced for driving; sequence switch 500 out of position 9, and the switch will continue to advance under the influence of its master cam 501 through inten mediate positions into position 12. Upon reaching position 10 a new holding' circuit is established for relay 518 extending trom grounded battery through the lett hand winding ot relay 518, the lower right hand Contact ot sequence switch cam 515 (1() to 11), the left hand armature and front con-- tact of relay 518 and thence to ground at the upper lett hand contact ol sequence switch cam 508. Upon reachingl posicion 11 sequence switch 500 establishes a new holding circuit for relay :318 extending Yfrom ground through the winning 0;? test inlay 524, conductor 5111, the upper left hand contact of sequence switch cam 502 (11 to 13), the lower lett hand contact of sequence switch cam 503 (11 to 13)., the right hand winding of relay 518, the upper right hand Contact of sequence switch cam 510 (11 to 12%), the right hand arma ture and 'liront contact 01 relay 518, the right hand contact of sequence switch cam 513?l test brush 542 and thence to grounded battery on the test terminal 560 oi the set oi terminals upon which the tripped set et brushes of the iinal selector switch has been set. llt is to be noted in this connection that all blank bank terminal sets will be grouped together and, with the exception of the last terminals of the group? which are connected to trunks extending to an intercepting op erators position7 all test terminals will be permanently connected to grounded battery over conductor 561 and tirough resistance elements 60() and 601, The battery potential supplied to these test terminals will be reduced since it is applied through both re sistance elements GOO and 601,

The ci'i'rent now flowing over the locking` circuit of relay 518 and through the windine; of rel-ay 59A is not sutticient tolenergize rela;f

521i since this relay is marginally wound7 but the current is suiiicient to maintain the energization ot relay 518. lilith sequence switch 500 in position 125 test relay 524- deenergized and relay 518 energizedj a circuit now es tablished for the updriye magnet 539 which may b traced from grounded ry nacer/si through the winding o1 .magnet 539, the lower lett hand contact oli sequence switch cam 507 (12), conductor 52?; the lett hand armature and Yfront eoiitact of relay the lower lett hand contact ot sequence switch cam 508 (12) and thence to grounl at the right hand ture and it'ront contact ol relay 521. energrixation o the updrire nialegnet ooi) cans the switch shait Sii? to be moved upwardly in a lnfnting` moreiuent. 'i n the test brush 5112 ou the next test terminal which test te' ,.ial corresponds Vto a second olf blank terminals and there-tore n'iuli; iled to the conouetor 3.61` the line relay 51S is main tained ener t f The d and suli'icient current does not flow to enorm e 5211- and therefore the switch shaft continues to more upwardly until the bri ,i es of the switcl encounter the set ot tei 5627 an Y. This set 8 ,i termr shown connecL to the iirst oiI a grow' trunk lines emendi to an intercept i p' :orle position. lt will be assumed y this trunk line is in use on another intercepted call and that therefore busy battery p l te y et this trunlr over a circuit which may be traced grounded batter)y through the contac s et sequence switch cams elector switch which has been set upon multiple terminals of the tiunlsV line. correspending` to cams and tl a in.

test brush of such other selector anc. to the multi e ot' lerniinal A lun current Y is diverte-l the winding' oi? relay 518 and the win Yn ot relay :i241- but the curr flowing over this circuit is sti Fui ze the test 521i.

.e will con,

er tie terni" i lines the group terniinat1 ceptinuV opel )s position.

ililhen the tes brush which it will he olf i tl n I test termii line extent, positioin groi" Y 12o tered on this test preyioi, f relay 518 will be opei deenertgiae o Y, r magnet cl seouenco switch 50o int-o neer grot l hand 

